1. Field of Invention
The present invention relates to a light emitting device, and more particularly to a flip-chip bonded light emitting device, in which light emitting diodes (LEDs) in the light emitting device are selectively connected in series or/and in parallel.
2. Related Art
Light emitting diodes (LEDs) are advantageous in low power consumption, high efficient and long service life, and thus are broadly applicable to various application fields, for example, light sources used in backlight modules of notebooks, monitors, cell phones, televisions, and liquid crystal displays. Further, more and more researchers and developers are devoting themselves to the research and development of the LED, such that the intensity of the current LEDs is sufficient for illumination.
In a conventional LED structure, a single-chip LED is disposed on a semiconductor substrate, with positive and negative poles of the LED chip facing upwards, the positive and negative poles of the chip are then electrically connected to pins through wire bonding, and the entire is encapsulated to form a complete LED encapsulation. The conventional LED structure forms the encapsulation by using only a single chip, and the light source generated thereby is not intense enough, thus cannot satisfying current requirement on high brightness.
Therefore, an LED die provided with a plurality of LEDs therein is developed, and the LED die is bonded to a submount through flip-chip bonding.
The conventional LED has a driving voltage approximately ranged from 3 volts to 4 volts, and the LEDs in the LED die are connected in series. Therefore, manufacturers may design LEDs of different numbers in an LED die, so as to connect in series to obtain a high voltage light emitting device, such that single light emitting devices may emit more intense light source, thus providing higher light emitting performance.
However, during manufacturing of LEDs in the conventional LED die, the LEDs are electrically connected in series in advance, so the manufactured light emitting devices all have a fixed driving voltage value. If light emitting devices having different driving voltages are required, LED dies of different specifications must be manufactured correspondingly, which has poor design flexibility and increases the manufacturing cost.